Electrochemical-catalytic NH3 synthesis from H2O and N2 using an electrochemical cell with a Ru catalyst, Pd-Ag membrane cathode, and NaOH-KOH molten salt electrolyte at 250 °C

Using sustainable energy-based electricity to synthesize NH3 from H2O and N-2 to release O-2 not only contributes to making chemical fertilizer production carbon neutral, but also holds promise for the use of NH3 as a fuel. NH3 synthesis from water and nitrogen was conducted at around 250 degrees C and below 1.0 MPa by combining a molten salt electrolyte of NaOH-KOH, a Pd alloy hydrogen-permeable membrane cathode, a Ni anode, and a Ru-based catalyst on the cathode backside. The rate and current efficiency for NH3 formation were obtained as 11 nmol s(-1) cm(-2) (38 mu mol h(-1) cm(-2)) and 25%, respectively, at 30 mA cm(-2), 1.0 MPa, and 250 degrees C. It was confirmed that the remaining percentage from the 100% current efficiency for NH3 production was attributed to the current efficiency for H-2 production. The cell voltage was as low as 1.47 V at 30 mA cm(-2) and increased to 1.95 V at 100 mA cm(-2). The potential of this electrochemical system is discussed.